As renewable energy production in the United States continues to grow, wind farms figure to remain a fixture of the Wyoming landscape in coming decades.
The United States currently gets 5.8 percent of its energy from renewable sources such as wind and solar, and the U.S. Department of Energy has said it hopes to increase that to 20 percent by the year 2030.
At the same time, scientists are still learning how wind turbines change the environment around them, perhaps affecting even the smallest creatures that share the space.
“Our main goal is to get managers the best information out there, so they can make the best decisions,” said Lusha Tronstad, lead invertebrate zoologist for Wyoming Nature Diversity Database. “So that wind farms and wildlife can co-exist.”
Tronstad, working with several graduate and undergraduate students from the University of Wyoming, has begun researching ways that wind farms might change nearby plant and insect communities. The group has been collecting insects around two wind farms in southern Wyoming for the last two summers. Another student has been gathering baseline information about pollination activity near wind farms.
Tronstad said she hasn’t found any other published studies about wind farms related to plants or insects.
While wind turbines occupy a fairly small amount of space on the ground, leaving room for farming and grazing operations below them, they do occupy a large swath of air space. A typical 1.5-megawatt tower is 212 feet tall, with its 116-foot blades reaching as high as 328 feet. The blades themselves spin over about an acre of area when moving. Scientists know that birds and bats are killed by wind turbines, Tronstad said, with birds usually killed by striking a blade.
Bats, which die at a rate seven times higher than birds, are killed when the moving blades cause a drop in air pressure, bursting blood vessels in their lungs. They are usually found near wind farms in the late summer, possibly as they follow migrating moths.
Do turbines affect other types of animal or plant life?
“Little else is known,” Tronstad said.
Some scientists hypothesized insects might be attracted to wind farms, either because of the color of the blades, the heat put out by turbines, blinking lights atop the hubs that flash at night, or their location atop ridges.
“If there are more insects (near wind farms), we have no idea,” she said.
Scientists do know that insects affect wind farms, however, by decreasing turbine efficiency. When their carcasses collect along the surface of the blades, the blade’s smooth surface becomes rough, swirling the air and decreasing power output by up to 50 percent.
“Wind farm operators need to clean the blades periodically,” Tronstad said.
Scientists also know that turbines cause a decrease in wind speed at the height of the hub, and turbulence from a turbine mixes air layers. Turbines cause downwind changes such as an increase in precipitation, temperature and evaporation. Some research has found such wake effects as far as 20k downwind of a wind farm location.
“We do know there are changes to the environment,” Tronstad said.
Tronstad’s preliminary research in possible changes to insect communities has focused on pollinators, such as bees, because of their importance to plant life.
About 90 percent of plants require the assistance of pollinators. Bees are the most effective pollinators.
“Their life is closely tied to flowering plants,” Tronstad said.
At their study area, Tronstad and her students estimated bee abundance at locations upwind and downwind of wind farms, as well as at the farms. They also estimated bee abundance on ridgetops, middle slopes and in valleys.
Elevation can change moisture, soil type, wind and vegetation. Bees are also sensitive to flower abundance, temperature and distance to water. They found bees to be most abundant at the middle elevations.
“There’s a lot of things that vary between the top of a hill and the bottom,” Tronstad said.
When sampling for other insect life using sticky traps and sweep nets, they found similar numbers of insects at upwind sites and at farm sites, though there was more variance among the farm sites.
UW student Lauren Thelen-Wade has been researching the plains prickly pear and whether its pollination effectiveness changes depending on its location relative to wind farms.
Bees visit the plant’s large flowers, which bloom for a single day, to gather pollen during late June and early July.
Thelen-Wade studied prickly pears found at the wind farm as well as at downwind and upwind sites.
She left some plants to pollinate on their own, covered some plants with fabric to prevent pollination, and hand-pollinated others.
Those pollinated by hand receive the most possible pollen. If the naturally pollinated plants differed in the number and weight of seeds compared to those pollinated by hand, then she would know that the natural pollination process wasn’t as efficient as it could be, a result known as pollen limitation.
Thelen-Wade found potential pollen limitation at the upwind sites, but no pollen limitation downwind. Seed mass was similar at all three sites. The bagged plants at the wind farm did develop seeds despite no access to pollinators, which was a surprising result.
Thelen-Wade said next steps could be to compare her data with wind data and information about bee abundance.
Tronstad said the research is in the preliminary stage so far, but she’s expecting to learn more throughout the next couple years.